Field of the Invention
The present invention relates to a developer agitating system, an electrophotographic image forming apparatus, and a cartridge.
The electrophotographic image forming apparatus forms an image on a recording medium through an electrophotographic image forming process. For example, the electrophotographic image forming apparatus includes an electrophotographic copying machine, an electrophotographic printer, such as an LED printer or a laser beam printer, an electrophotographic facsimile machine, and an electrophotographic word processor.
The process cartridge makes charging means, developing means or cleaning means and an electrophotographic photosensitive member integrally into a cartridge that is detachably mountable to a main body of the electrophotographic image forming apparatus, or makes at least one of the charging means, the developing means and the cleaning means and the electrophotographic photosensitive member integrally into a cartridge that is detachably mountable to the main body of the electrophotographic image forming apparatus, or makes at least the developing means and the electrophotographic photosensitive member integrally into a cartridge that is detachably mountable to the main body of the electrophotographic image forming apparatus.
The developing cartridge is directed to a cartridge that includes at least the developing means and is detachably mountable to the main body of the electrophotographic image forming apparatus.
Up to now, a two-component developing device has been widely employed as an electrophotographic developing device. This is because the electrostatic charging property of the toner is remarkably excellent. FIG. 5 shows an example of a general two-component developing device.
Referring to FIG. 5, a two-component developing device 111 includes a developer container 110 that contains a developer therein and a developing sleeve 102 that serves as a developer bearing member and is rotatably supported on an opening portion of the developer container 110. The developing sleeve 102 is formed of a hollow metal sleeve and surrounds a magnet roller 103 therein.
Also, first and second agitating screws 105 and 106, which serve as agitating means, are disposed within the developer container 110 so as to be substantially in parallel with the developing sleeve 102, and more specifically, the first agitating screw 105 is disposed in the vicinity of the developing sleeve 102, whereas the second agitating screw 106 is disposed far from the developing sleeve 102.
Further, as is understood from FIG. 6, the first and second agitating screws 105 and 106 are partitioned by an inner wall 107 so that the developer is not delivered between both the first and second screws 105 and 106 while the developer is being carried, and the developer can be delivered between the first and second agitating screws 105 and 106 through opening portions defined between both end portions of the inner wall 107 and the developer container 110. Then, because the first and second agitating screws 105 and 106 are so designed as to carry the developer in opposite directions, respectively, a circulating path is produced within the developer container 110, which allows the developer to circulate therein without being interrupted as indicated by arrows.
An inductance sensor 112 for detecting the ratio of non-magnetic toner to magnetic carriers (hereinafter referred to as xe2x80x9ctoner densityxe2x80x9d) which are formed into a two-component developer is disposed upstream of the second agitating screw 106 in the developer carrying direction as toner density detecting means. Because the permeability of the developer is determined by the amount of carriers contained in a given volume, the toner density can be detected by measuring the permeability of the developer through the inductance sensor 112.
A toner replenishing port 108 is disposed slightly downstream of the inductance sensor 112. When the toner is used for image formation and the toner density in the developer decreases, the decreased amount of the toner density is measured by the inductance sensor 112 when the developer passes through the inductance sensor 112. Then, an appropriate amount of toner is replenished to the developer container 110 through the toner replenishing port 108 from a toner replenishing mechanism 109 mounted on an upper portion of the developer container 110 so that the toner density of the developer is maintained at a constant value.
There are many cases in which the developing device is detachably mountable to a main body of an image forming apparatus as a developing cartridge so that a user per se can replace the developing device by a new one.
Incidentally, the most significant advantage of the developing cartridge (or process cartridge) resides in the fact that the cartridge can be replaced by the user per se. In the most cases, the developing cartridge is kept in its attitude in which the developing cartridge is set within a packaging box. However, in the case where the developing cartridge is kept for a long period of time in a state where the developing cartridge is set vertically as shown in FIG. 7, there is a fear that a developer T is extremely one-sided in its longitudinal direction within the developer container 110.
As a result, there may unavoidably occur disadvantages such that the toner density becomes non-uniform, the replenished toner is not well mixed with the developer, or the like.
The above disadvantages may be applied to not only the developing cartridge but also the process cartridge.
The present invention has been made in order to solve the above problems, and therefore an object of the present invention is to provide a developer agitating system, an electrophotographic image forming apparatus, and a cartridge that are capable of returning the developer to an appropriate state even if the contained developer is one-sided.
Another object of the present invention is to provide a developer agitating system, an electrophotographic image forming apparatus, and a cartridge, which detect whether there is provided a given cartridge, that is, a cartridge where developer in a developer containing portion is not consumed at all, or not, and agitate the developer for a period of time corresponding to a detected result.
Still another object of the present invention is to provide a developer agitating system, an electrophotographic image forming apparatus, and a cartridge, which detect whether there is provided a given cartridge, that is, a cartridge where developer in a developer containing portion is not consumed at all, or not, and agitate the developer for a long period of time as compared with a case in which the given cartridge is not provided if the given cartridge is provided.
Yet still another object of the present invention is to provide a developer agitating system, an electrophotographic image forming apparatus, and a cartridge, which detect whether there is provided a given cartridge, that is, a cartridge where developer in a developer containing portion is not consumed at all, or not, agitate the developer for a long period of time as compared with a case in which the given cartridge is not provided if the given cartridge is provided, and thereafter measure the density of developer.
Yet still another object of the present invention is to provide a developer agitating system, an electrophotographic image forming apparatus, and a cartridge, which measure the density of developer after agitating the developer, and store the measured density of developer as a standard density in a memory.
Still another object of the present invention is to provide a developer agitating system, an electrophotographic image forming apparatus and a cartridge, which detect whether there is provided a given cartridge, that is, a cartridge where a developer filled in a developer containing portion is not consumed at all, or not, and agitate the developer for a long period of time as compared with a case in which the given cartridge is not provided if the given cartridge is provided.
Yet still another object of the present invention is to provide a developer agitating system, an electrophotographic image forming apparatus and a cartridge, which detect whether there is provided a given cartridge, that is, a cartridge where a developer filled in a developer containing portion is not consumed at all, or not, agitate the developer for a long period of time as compared with a case in which the given cartridge is not provided if the given cartridge is provided, and thereafter measure the density of developer.
Yet still another object of the present invention is to provide a developer agitating system, an electrophotographic image forming apparatus and a
These and other objects, features and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.